The compound 1,1,1,3,3-pentachloropropane (HCC-240fa) is a raw material for producing 1,1,1,3,3-pentafluoropropane (HFC-245fa), which is a non-ozone depleting chemical and can be used as blowing agent, energy transfer medium, and so on. Addition reactions for preparing useful haloalkanes, such as HCC-240fa, are known in the art. For example, U.S. Pat. No. 6,313,360 teaches a process for producing HCC-240fa by reacting carbon tetrachloride (CCl4) and vinyl chloride monomer (H2C=CHCl or VCM) in the presence of a catalyst mixture comprising organophosphate, e.g., tributylphosphate (TBP), metallic iron and ferric chloride under conditions sufficient to produce a product mixture containing HCC-240fa. The 240fa product is then recovered by separating it from reactants, catalyst and by-products. See also, U.S. Pat. Nos. 5,902,914, 6,187,978, and 7,102,041. See also, U.S. Patent Publication No. 2008/0091053, and EP Patent Pub. No. 729932. The disclosures of all of these references are hereby incorporated herein by reference.
VCM is a liquefied gas and a precursor to polyvinyl chloride (PVC), a potential undesired solid by-product in the production of HCC-240fa. Indeed, it was observed that the addition of liquid VCM to a reactor containing CCl4, TBP, and Fe0 resulted in a significant exotherm and the formation of excessive amount of solid material characteristic of PVC. The detrimental impacts of the formation of PVC include:
(1) yield loss,
(2) difficulty in heat management, and
(3) reduced catalyst activity (iron particles may be encapsulated by PVC).
Therefore, the present applicants have come to appreciate the need for means by which the formation of PVC in HCC-240fa production process can be avoided. The present invention solves this problem.